How the Web Works

Getting a web app from it's host to a user is a series of lightning fast transactions, initiated from the user and executed by the code in our web app. Server and data-center performance is part of the solution, which is out of scope of this course, but once the server replies to the request of the user, let's just say, the less we can send, the better.

New Terms:

Front End Performance Optimization -- The modification of HTML, CSS, and JavaScript (and sometimes, server configuration) for the purpose of improving page load times.SPDY -- The now deprecated project, Google’s next generation Transfer Protocol for web trafficHTTP/2 -- Official next generation Transfer Protocol, based on SPDY created by GoogleHTTP Header Request -- Information passed between the client and server during a web requestHead of Line Blocking -- a web performance limiting issue where a request may be stuck waiting for another request to be completed before it can beginLoad time -- the total time it takes for a web app or site to loadLatency -- An issue related to Head of Line Blocking where time is added to the total download time of a web site waiting to download additional assetsPerformance Budget -- The total allowed page weight of your site or appGZip -- A popular server side compression methodBrotli -- A newer server side compression method developed by GooglePerceived Performance -- A metric for how fast user’s think your site isFirst Meaningful Paint -- A perceived performance metric where the user first sees content appear in the client post requestFirst Available Interaction -- A metric that closely associates with First Meaningful Paint where the user is able to begin interaction with the content of your site/appAbove the Fold(AtF) -- CSS, Images and JavaScript that are essential to the initial load of the site or app within the constraint of the first view